Differential piston pump



NOV- R. J. LlNnsEY 2,861,520

DIFFERENTIAL FIsToN PUMP Filed July 19, 1954 L W 79g gg 30 Y INVENTM ,251.1 78 M fha/HQ gru DIFFEREN'HAL PISTON PUMP Robert .1. Lindsey,Cincinnati, Ohio, assignor to American Iteel Foundries, Chicago, Ill., acorporation of New ersey Application July 19, 1954, Serial No. 444,005

4 Claims. (Cl. 10S-153) This invention relates to a fluid pump and moreparticularly to a reciprocating plunging type pump especially adapted togenerate high working pressures.

Conventional pumps heretofore employed in the art have presented aproblem when it is desired to develop high working pressures. lf theworking area of the fluid contacting piston is relatively large, anextremely expensive drive or power source is required to develop thepower necessary to reach the desired working pressure. This additionallyentails increased size and strength of connecting mechanism such ascrank arms and bearing areas in order to adequately carry the requiredload, which also adds additional expense to the units and renders saidunits undesirable from a size standpoint. The alternative to theseundesirable features usually practiced in the art, is to materiallyreduce the piston or plunger area by designing it to be a long slenderrod whereby high working pressures may be developed on a relativelysmall fluid working area, thereby avoiding the increases in size andpower mentioned above. It has been found, however, that this alternativeis not without operating diiiiculties, the most .prominent being thatthe rod or plunger employed frequently fails from buckling due to therelatively high column or compressive loads.

Accordingly, it is a primary object of the invention to provide a pumpof the type described wherein the mentioned difficulties are solved.

It is another object of the invention to provide a pump of the typedescribed which employs a differential piston plunger to alleviate thementioned problems.

It is the specific object of the invention to provide a pump of the typediscussed wherein the piston rod or plunger is provided with a guidetail or rod whereby the plunger presents a relatively small workingarea, thus developing high working pressures, while the rod itself isrelatively heavy in section thus eliminating the prior art tendency tobuckle under axial loading.

These and other objects of the invention will become apparent from anexamination of the following specification and the associated drawing,wherein:

The ligure is a vertical sectional view through a typical pumparrangement embodying the invention.

Describing the invention in detail and directing attention to the gureassociated herewith, it will be seen that the pump arrangement comprisesa base 2, said base 2 having a lower section 4 and upper section 6. Theupper section 6 may be considered as the working section of the pump andis provided with a working chamber indicated by the numeral 8. Onopposite sides of the section 6, the pump presents an intake port 10 andan exhaust port 12, respectively. A iiuid passage 14 is provided in thesection 6 and establishes communication between the intake port 10 andthe chamber 8. An additional uid passage 16 is provided to establishcommunication between the chamber 8 and the exhaust port 12.

The section 6 is additionally crossed drilled at 18 ICC and 20,respectively, said crossed drilled holes extending into the passages 14and 16, respectively. The hole 18 is provided with an vinsert Y22 whichmay be secured to the section 6 by conventional cap screws 24, saidinsert 22 providing a seat for a one-way check valve 26 which isdisposed in passage 14 intermediate the chamber 8 and intake port 10.The hole 20 is also provided with an insert 28, said insert beingconventionally secured to the section 6 by cap screws 30. The insert 28provides a seat for another one-way check valve 32, said check' valve 32being located in the passage 16 intermediate the chamber 8 and exhaustport 12. It will be noted that the check valve 26 accommodates fluidflow from the intake port 10 tothe chamber 8 and prevents a reversal ofsaid liuid flow, while the check Valve 32 accommodates fluid ow from thechamber 8 to the exhaust port 12 and prevents a reversal of fluid flow.

Section 6 is additionally provided with a crossed drilled aperture 36,said aperture being located centrally of the section and verticallyaligned with the chamber 8. A guide bushing 38 is disposed in thedrilled hole 36 at the lower end thereof and conventional packing glands40 are disposed in the hole 37 immediately above the bushing 38. Aninsert 42 is provided to closey the upper end of the hole 36 and toretain the packing 40 and bushing 38 iixedly in position. The bushing38, packing 40, and insert 42 are provided with centrally aligned holeswhich complementally receive a segment of an operating piston or plunger44, the lower end of said plunger extending into the chamber 8. Theplunger 44 can be seen to comprise a relatively large segment 46 and asmaller segment or tail rod 48 connected to the lower end of the segment46 at a point disposed with the chamber 8. The Atail rod 48 extendsdownwardly Whereat it is received within a guide bushing 50, packingglands 52, and insert 54, the bushing, packing glands, and insert beingixedly disposed in an aperture in section 6 of the base 2. Thus it willbe noted that the piston rod 44,is guided for linear movement within thebase 2 at a pair of spaced points.

The upper end of the piston 44 is operatively connected to a linearlymovable head 56, said head 56 being received within a'guiding frame 58provided in the pump. The head 56 is pivotally connected to the lowerend of a connecting rod 60 by means of a piston pin 62. The upper end ofthe rod 60 is conventionally split to form a lower section and cap whichengage a throw 64 of a crank 66 as will be well understood by thoseskilled in the art. The crank arm 66 is, of course, operativelyconnected to a power source (not shown) whereby the throw 64 iseccentrically rotated about the center or rotational axis of the crank66, thus imparting linear reciprocal movement to the head 56 and to theconnected piston 44. Conventional lubricating devices 68 and 70 areprovided to properly grease operating surfaces of the frame 58.

Directing attention to the piston 44 and particularly the segments 46and 48, it will be seen that a working area 71 is provided on the end ofthe segment 46, said Working area being determined by the difference incross sectional areas or sizes of the respective segments 46 and 48. Theworking area of the piston could reasonably be denominated adifferential pressure area. It will be noted that through thisconstruction, the working area 71 is considerably smaller than the crosssection area of the relatively large section 46, thus providing asmaller working area whereby relatively high working pressures may bedeveloped in the chamber 8 by the piston 44 while the piston andespecially the segment 46, which is subjected to the operating load incompression,

is of relatively large cross section area and 'therebybetter able towithstand the axial loads applied thereto.

In operation, the throw 64 is rotated in the direction of the arrow d ueto rotation of the crank 66.' This in turn causes the head S6 toreciprocate vertically within the guiding means 5,8, and thisreciprocating action is transmitted to the connected piston 44. Thereciprocating action of the piston 44 on its upper stroke draws fluidfrom the intake port 10 past the check valve 26 and into the chamber 8,the check valve 32 preventing fluid ow in the passage 16 in thedirection of' chamber 8. On the downward stroke of thepiston 44, thedifferential piston area 71 operatively works on the fluid in chamber 8thereby increasing the pressure of said uid to the desired level andforcing the uid through passage 16 and outwardly through the exhaustport 12 past the one-way check valve 32. Theaction is repeated througheach complete cycle of the piston 44 whereby a continuous volume of highpressure fluid is delivered tothe exhaust port.

Thus it will be seen that I have provided a reciprocating type pumparrangement capable of delivering high working pressures and one notsubject to failure through buckling tendencies of similar pumpsheretofore employed in the art. Additionally, the arrangement does notrequire extremely large or powerful power sources to deliver the desiredworking pressures.

I claim:

1. vA reciprocating high pressure plunger type pump comprising incombination, a base, a guide frame mounted in said base, a head slidablyreceived in said guide frame, power means operatively connected to thehead to reciprocate the head in said guide trame, a working chamber insaid base, said chamber having an inlet and an exhaust port, a plungersecured to and movable with said head, said plunger having a bodyportion and a tail portion of smaller diameter than said body portion,the juncture of said portions, being disposed in said chamber to form ahigh pressure working area therein, guide means and packing glands inthe base above said chamber slidably receiving said body portion, andguide means and packing glands in the base below said chamber slidablyreceiving said tail portion.

2. A reciprocating high pressure plunger type pump according to claim l,and including one-way check valves in respective ports accommodatingflow of fluid through said chamber in a common direction.

3. In a reciprocating high pressure plunger type pump, a base, a guideframe mounted in said base, a head slidably received in said guideframe, power means operatively connected to the head lto reciprocate thehead in said guide frame, a working chamber in said base, a plungersecured to and movable with said head, said plunger having a bodyportion and a tail portion of smaller diameter than said body portionthereby defining a high pressure working area, guide means and packingglands carried by said base and slidably receiving said body portion andother guide means and packing glands `carried by said base and slidablyreceiving said tail portion.

4. A reciprocating plunger type pump operable to develop high workingpressures, said pump comprising a base, a chamber in the base, an intakeport in said base, a check valve operatively connecting said chamber andsaid port and accommodating flow of fluid only from the port to thechamber, an exhaust port in said base, a check valve Yopaeratrfslyconnecting said chamber and said exhaust port and accommodating how offluid only from the chamber to the exhaust port, a guide frame carriedin said base, a reciprocating head slidably received in said guideframe, power means operatively connected to said head, a plungeroperatively secured to said head and guidably received in an aperture inthe base, said plunger extending into the chamber, an end on theplunger, said end being disposed in the chamber, a tail rod xedlyconnected to the plunger centrally of the end, said rod being smallerthan the end of said plunger, said rod being guidably received inanother aperture in the base, and packing glands carried by the base andoperatively associated with said plunger and said rod to prevent thellow of high` pressure uid past Vsaid plunger and said rod,respectively.

References Cited in the file ot" this patent UNITED STATES PATENTS364,258 Keating June 7, 1887 1,724,156 Winton Aug. 13, 1929 2,733,664-lsaa1frank Feb. 7, 1956 l FOREIGN PATENTS 117,212 switzerland oct. 16,192s" 506,210 Belgium Oct. 3l, 1951

